Diagnostic Medical Device
Diagnosis of physiological conditions by observing color, texture, and appearance of the skin, especially of the face, is a technique that has been used by physicians for generations and retains an important role today. Thus, the Medline Plus Medical Encyclopedia provided by National Institutes of Health advises physicians to “look for the presence of a pale complexion” when diagnosing sickle cell anemia. The NHS Direct Online Health Encyclopedia notes that “gray complexion” is a symptom of an impending heart attack. An online publication from the Dr. Joseph F. Smith Medical library discloses that “in many cases the diagnosis of jaundice is suggested by the appearance of the patient's eyes and complexion.” The General Health Encyclopedia provided by Adam Inc. notes that a “very ruddy red complexion (plethoric)” is a symptom of hyperviscosity.
The aforementioned techniques require an actual human physician to view the patient or an image of the patient and to make the diagnosis. The human physician views the patient in sunlight or in a lit room, senses the color, texture, and appearance of the skin using photoreceptors within his or her retina, and analyzes the biofeedback of the skin to a natural continuous light (sun light) or artificial continuous or discontinuous spectrum of light in order to make a diagnosis. Unfortunately, human physicians are limited to light in the visible spectrum, are expensive, and prone to errors.
Historically, medical diagnosis was the domain of human physicians unaided by electronic devices. In the past century, with the advent of electric and electronic diagnostic devices, these devices have played a more prominent role. One example of such a diagnostic device is the oximeter for measuring the oxygen status of blood. In contrast to the human retina which is configured to detect continuous or discontinuous spectra of light, oximeters provide a coherent light source for emitting light at a pre-specified wavelength, and a detector for detecting light at this wavelength.
Pulse oximetry is a widely accepted noninvasive procedure for measuring the oxygen saturation level of arterial blood, an indicator of oxygen supply. A pulse oximetry system generally consists of a probe attached to a patient, a monitor, and a cable connecting the probe and monitor. Conventionally, a pulse oximetry probe has both a coherent lightsource such as an LED for emitting red and/or infrared light of predetermined wavelengths and a photodiode detector. The probe is typically attached to a patient's finger or toe, or a very young patient's foot. For a finger, the probe is configured so that the emitters project light through the fingernail, the arteries, vessels, capillaries, tissue and bone. The photodiode is positioned opposite the LED so as to detect the LED transmitted light as it emerges from the finger tissues.
The pulse oximetry monitor (pulse oximeter) determines oxygen saturation by analyzing the differential absorption by arterial blood of the two wavelengths emitted by the probe. The pulse oximeter alternately activates the probe LED emitters and reads the resulting current generated by the photodiode detector. This current is proportional to the intensity of the detected light. The pulse oximeter calculates a ratio of detected red and infrared intensities, and an arterial oxygen saturation value is empirically determined based on the ratio obtained. The pulse oximeter contains circuitry for controlling the probe, processing the probe signals and displaying the patient's oxygen saturation and pulse rate.
Pulse oximeters are described in U.S. Pat. No. 5,632,272, incorporated herein by reference in its entirety. US 2003/0009090 discloses an oximetry device which purportedly incorporates effects due to light scattering by red blood cells.
Oximeters are based upon the Beer Lambert law, which is given by:
                                          c                          HbO              2                                                          c                              HbO                2                                      +                          c              Hb                                      =                                                                              A                  1                                ⁢                I                            -                              A                2                                                                                      B                  1                                ⁢                I                            -                              B                2                                              .                                    (                  1          ⁢          a                )            
The parameters A1, A2, B1 and B2 depend on the light absorption at two distinct wavelengths λ1 and λ2, while the ratio between absorption at two different ratios is given by I
                    I        =                                            log              ⁡                              (                                                      I                    1                                    ⁢                                      ⅇ                                                                  -                                                  <                                                      A                            _                                                                                              ,                                                                        C                          _                                                >                                                                                            )                                                    log              ⁡                              (                                                      I                    2                                    ⁢                                      ⅇ                                                                  -                                                  <                                                      B                            _                                                                                              ,                                                                        C                          _                                                >                                                                                            )                                              ..                                    (                  1          ⁢          b                )            
The symbol cHbO2 represents the oxyhemoglobin concentration (HbO2) and cHb represents the reduced hemoglobin concentration Hb.
The pulse of the subject can be determined by observing temporal patterns in an instantaneously measured arterial blood oxygen saturation level.
There is an ongoing medical need for non-invasive devices for detecting physiological information of a subject. Preferably, these devices would incorporate low cost, readily available components. Preferably, these non-invasive devices would also be operative at a distance from the subject, obviating the need to physically attach specific probe to the subject. Preferably, these non-invasive devices would be operative to detect a wide range of physiological indications.
Devices for Estimating Relevant Biophysical and Biochemical Parameters in Food and Beverage
There is an ongoing need for techniques for analyzing relevant biophysical and biochemical parameters of food and beverages, especially perishable items such as fruit and vegetable produce, perishable dairy products, meat and fish products as well as less perishable items such as wines such as wines provided within sealed bottles. Although it is known that wine color in some situations can be a good predictor of wine quality, assessment of wine quality from visual characteristics of wine requires trained experts who are limited to subjectively reporting qualitative characteristics rather than a quantitative indication of wine quality like a pH. Furthermore, it is known that a spoilage status of food such as meat is also related to meat color. For the specific case of beef, psychrotrophic bacteria at the meat surface leads to oxidation of meat pigments which results in a progressive deterioration of the acceptable red color and the appearance of varying degrees of brown surface discoloration.
There is an ongoing need for methods and apparatus for detecting biophysical properties of food products and beverages.
Devices and Methods for Estimating Relevant Biophysical and/or Biochemical Parameters in Environmental Contamination
Chemical contamination and environmental pollution threatens our existence everyday, everywhere. There is an ongoing need for environmental hazard detectors, and in particular, cost effective, easy to operate of environmental hazard detectors. For example, there is an ongoing need for devices and methods for detecting a level of contaminative substances in liquids and/or in gases. For example, there is an ongoing need for devices and methods for detecting a level of air pollution.